"It's a fairly complex process as to why we think people will go on [using].

"We know the reasons why people initiate drug use on the whole have got to do with peer pressure, curiosity, in some cases there may be some emotional soothing behaviours as well."

Those who used drugs recreationally were likely to have curious or risk-taking personalities, Dr Lennings said.

But the reason people maintained drug use or became dependent came down to a range of factors, including genetic function which appeared to heighten the positive effects of drugs.

"For some the experience is much more positive than for others and these people appear to have a much higher risk going on to dependent drug use.

"Others are people who are experiencing ongoing stresses and traumas that they're unable to successfully resolve, perhaps because of the environment they're living in or perhaps because of functions in their personality that make it more difficult for them to resolve trauma."

Some of those people had higher mental needs for dependence, whether that be on people or substances, while others lacked the ability to manage their emotions and needed external methods like drugs, Dr Lennings said.

Pharmacology of drugs also had an impact, illustrated by the addictive nature of heroin, methamphetamine and cocaine, compared to the low dependence potential for cannabis, she said.

"There are issues that I would argue come into play, things like mental health and background."

Professor Michael Farrell, the director of the National Drug and Alcohol Research Centre in the University of NSW, said drug use was far removed from the stereotype of kids rebelling against their parents.

"One of the myths of a decade ago was that kids want to rebel against family values, whereas one of the things we would be far clearer about now is that kids do tend to adopt parental values.

"The type of support and supervision they get can make a huge difference in how they fare in their exposure.

"That does not, by any stretch of the imagination, mean that none of them go out and do risky things.

"But it may mean the difference between them doing risky things as compared to getting in significant trouble with them."

Families that communicated openly and supported each other could be protective against heavy or ongoing drug use, along with education and social connections, he said.

"It isn't necessarily associated with an economic thing. You could have a family that is quite well off but doesn't have good communication within it, and so the nature of what is a good family can be complex.

"There's a lot of luck in life. If you're in a reasonable neighbourhood and the school is OK, if you're a certain type of person you might not get into the trouble you might have otherwise got into."